1. Technical Field
The present invention relates to a semiconductor device and a method of manufacturing the same.
2. Related Art
There are known techniques of mounting a semiconductor element on a substrate, and then encapsulating it using an encapsulation resin to thereby form a semiconductor package. The conventional encapsulation has been carried out using a single species of resin composition. However, under the presence of bonding wires, it is now necessary to prevent the wires from flowing and falling down in the resin, in the process of encapsulating the semiconductor element using the encapsulation resin. On the other hand, it is also necessary to control warping behavior of the semiconductor package after the encapsulation. It has however been difficult to optimize the resin material which satisfies these requirements at the same time, by using only a single species of resin composition. For this reason, a large number of species of resin materials have been prepared and developed aiming at achieving the optimum characteristics, only to raise problems in large cost and poor productivity.
Japanese Laid-Open Patent Publication No. H08-162573 describes a semiconductor device which contains a semiconductor element bonded, while placing an adhesive layer in between, to a substrate having a circuit preliminarily formed thereon, and encapsulated by a cured, resin layer having a layered structure composed of an inner cured resin layer and an outer cured resin layer.
Filler content of the inner cured resin layer herein is set smaller than that of the outer cured resin layer. The publication described that, by virtue of this configuration, the semiconductor device which is successfully suppressed in the flowing of wires and reduced in the warping may be provided. The inner cured resin layer and the outer cured resin layer herein are formed by transfer molding.